1. Field of the Invention
The present invention relates to a fine powder material for forming an ink-receiving layer, a manufacturing method of the fine powder material, a recording medium making use of the fine powder material and an image forming method using the recording medium.
The ink-jet recording method is a method in which minute droplets of ink are ejected to recording media such as paper by various principles and adhered thereon to record images, characters and the like. Since this method features merits to allow various patterns to be recorded at high speeds, with low noise, in multiple colors and without development, the method is rapidly prevailing not only to printers but also to information apparatus such as copying machines, word processors, facsimile machines and plotters. Furthermore, in the recent years where high performance digital cameras, digital video scopes and scanners have been offered at low prices and personal computers have been widely prevailing, there have been increasing occasions to record image data obtained from these appliances by the ink-jet recording method.
Accordingly, there has been demanded ink-jet recording methods which are capable of providing images which are not inferior as compared with those of silver salt type photographs and plate-making type multi-color prints.
While recording apparatus and recording methods have been improved in recording images speedily and making high precise and multi-color images, there have been demanded upgraded characteristics of recording media.
2. Related Background Art
There have conventionally been proposed various recording media as those for the ink-jet recording. For example, Japanese Patent Application Laid-Open No. 52-53012 discloses a paper for ink-jet recording which is infiltrated with a facing paint into a lower-sized base paper. Japanese Patent Application Laid-Open No. 53-49113 discloses a paper for ink-jet recording which is impregnated with a water-soluble polymer into a sheet comprising urea-formalin resin powder. Japanese Patent Application Laid-Open No. 55-5830 discloses a paper for ink-jet recording which is provided with an ink absorptive layer on a surface of a substrate, Japanese Patent Application Laid-Open No. 55-51583 discloses an example that an amorphous silica is used as a pigment in a covering layer and Japanese Patent Application Laid-Open No. 55-146786 discloses an example in which a coated layer of a water-soluble polymer is used.
Alumina hydrate has recently been attracting attention as a material for composing a portion of a recording medium where an ink is received. This is because the alumina hydrate has positive electric charges and retains ink well, thereby being capable of providing images having a high coloristic performance and a high glossiness which are unavailable with conventional recording media. U.S. Pat. Nos. 4,879,166 and 5,104,730 and Japanese Patent Application Laid-Open Nos. 2-276670, 4-37576 and 5-32037 disclose recording media which use layers containing alumina hydrate of pseudo-boehmite structures as ink-receiving layers.
However, the recording media which use alumina hydrate as a material for the ink-receiving layers may pose problems enumerated below in certain cases of attempts made to record, in a far shorter time, highly precise images which are not inferior as compared with those obtained on silver salt type photographs and plate-making type multi-color prints.
(1) Since inks are supplied to the recording media in larger amounts per unit time for recording highly precise color images in a shorter time, printed ink cannot be absorbed completely by pores and flows over surfaces of the ink-receiving layers, whereby bleeding occurs to deteriorate qualities of prints.
(2) Beading occurs when ink absorbing speeds cannot sufficiently cope with high recording speeds though the recording media must have high ink absorbing speeds for recording at high speeds.
xe2x80x9cBeadingxe2x80x9d is a phenomenon that a preceding ink dot comes into contact with the next ink dot before being absorbed and fixed by a recording medium, whereby adjacent printed dots are connected to each other like beads and make an optical density of image uneven.
These problems are associated with each other and an absorbing speed is naturally tends to be higher as a recording medium has a larger ink absorbing capacity. However, certain recording media which have large ink absorbing capacities have slow ink absorbing speeds. Such a recording medium allows inks to be kept in conditions flowing over the recording medium before it completely absorbs the inks, when large amount of ink is applied. Accordingly, inks of adjacent dots are mixed with each other, thereby causing bleed in printed characters and color mixing in multi-color printing. As a result, the recording medium remarkably degrades qualities of prints and images.
Furthermore, relationship between ink absorptivity and color density must be taken into consideration in addition to the problems mentioned above.
The relationship is associated with a pore volume and its distribution of alumina hydrate. In order to enhance an ink absorptivity, it is usually sufficient to enlarge a pore volume. In other words, it is sufficient to shift a pore radius distribution toward a larger side. When a pore radius distribution (a pore radius maximum in particular) is shifted excessively toward a larger side, however, an image formed by the ink-jet method is made whitish as a whole due to irregular reflection or the like occurring in pores, thereby tending to hinder coloring property of dye and lower a color density.
As a measure to prevent such an adverse phenomenon, Japanese Patent Publication No. 57-44605 proposes a method to narrow a range of pore radius distribution by repeating a plurality of treatments and shift the pore radius distribution toward a larger side. When treatments are conducted to narrow a pore radius distribution, the distribution is usually shifted toward a higher pore radius maximum. However, such a method increases treating steps and allows a production amount of recording medium to be limited by a capacity of a reaction vessel which is installed first for batch system treatments. Accordingly, the method tends to enhance a manufacturing cost of the recording medium.
In contrast, a continuous method which is capable of producing a recording medium in a large amount, thereby making it possible to manufacture it at a low cost. However, alumina produced by such a continuous method has a wide pore radius distribution as a physical property thereof. This is because starting materials are put as occasion demands for production by the continuous method, portions at an advanced reaction stages are mixed with portions at initial reaction stages and crystals are grown unevenly, thereby widening a pore radius distribution. Accordingly, the alumina contains a large amount of components which have small pore radii within the large pore radius distribution and hinders absorption of inks, thereby having an unsatisfactory ink absorptivity. Furthermore, the alumina has an unsatisfactory color density since it has a pore radius distribution which covers large pore radii.
A primary object of the present invention is to provide a fine powder material which has an enhanced ink absorption speed while maintaining a favorable dye fixing property, excellent color density, high coloring property and high glossiness, allows printed dot to be formed with a high reproductivity and can be manufactured at a low cost, a manufacturing method of this fine powder material and a recording medium using the fine powder material. Another object of the present invention is to provide an image forming method by ink-jet recording using the recording medium.
According to the present invention there is provided a fine powder material for forming an ink-receiving layer of a recording medium, in which a pore radius maximum exists within a range of from 90 to 120 xc3x85 in a pore radius distribution of the fine powder material and a total volume of pores having radii not exceeding 50 xc3x85 is not more than 6.0% of a volume of all pores.
According to the present invention there is also provided a manufacturing method of fine power material in which a fine powder material having a pore radius maximum N1 in a pore radius distribution is secondarily treated to make a fine powder material having a pore radius maximum N2 in a pore radius distribution so as to satisfy an equation
N1≅N2 or N2 less than N1
and a total volume of pores having radii not exceeding 50 xc3x85 is not more than 6.0% of a volume of all pores after the secondary treatment.
According to the present invention there is further provided a recording medium provided with an ink-receiving layer comprising a fine powder material and a binder formed on a base material, wherein a pore radius maximum exists within a range of from 90 to 120 xc3x85 in a pore radius distribution of the ink-receiving layer and a total volume of pores having radii not exceeding 50 xc3x85 is not more than 10.0% of a volume of all pores.
According to the present invention there is still provided a recording medium provided with an ink-receiving layer comprising a fine powder material and a binder formed on a base material, wherein a pore radius maximum exists within a range of from 90 to 120 xc3x85 in a pore radius distribution of the fine powder material and a total volume of pores having radii not exceeding 50 xc3x85 is not more than 6.0% of a volume of all pores of the fine powder material, and wherein a pore radius maximum exists within a range of from 90 to 120 xc3x85 in a pore radius distribution of the ink-receiving layer and a total volume of the pores having the radii not exceeding 50 xc3x85 is not more than 10.0% of a volume of all pores on the ink-receiving layer.
The image forming method according to the present invention is a method in which recording is performed on the recording medium described above by an ink-jet recording method.